/Engine/Source/Runtime/Engine/Classes/Engine/NetDriver.h
NetClientTicksPerSecond is used to throttle how many clients are updated each frame, hoping to avoid saturating the server's upstream bandwidth, although the current solution is far from optimal. Ideally the throttling could be based upon the server connection becoming saturated, at which point each connection is reduced to priority only updates, and spread out amongst several ticks. Also might want to investigate eliminating the redundant consider/relevancy checks for Actors that were successfully replicated for some channels but not all, since that would make a decent CPU optimization.
the number of actors that were replicated
virtual int32 ServerReplicateActors ( float DeltaSeconds )